Sometimes you see a piece of theatre that makes your heart sing, makes you feel good about all of humanity, and makes you want to stand up and be counted. Nic Green's Trilogy is such a work. A strenuously choreographed, three-part, three-hour piece of participatory theatre that examines and celebrates what it means to be a woman in the 21st century, where we have come from and where we are going, Trilogy is angry, joyous, heartfelt, rigorous and radiant with hope. It makes you want to fling off your clothes and dance.

Each night, many women in the audience have done just that, joining in with the dancers on stage. Within the context of the show, it feels like nothing less than a political act. When you say a piece of theatre feels important, it makes it sound po-faced. Yet Trilogy wears its politics with a cheeky grin and a skip in its step.

Green and her young cast members were all born in the 1980s, but Trilogy is a reminder of the debt young women owe to those who came before them (whether that's your gran or Germaine Greer), as well as what has been forgotten or lost.

The first segment focuses on women and their relationships with their bodies, culminating in an extraordinary dance in which the naked power and energy of 50 unclothed, totally unselfconscious women blazes across the stage. In part two, the show goes back in time, drawing on archive footage from the famous 1971 Town Bloody Hall debate in New York about women's lib. It was chaired by a misogynistic Norman Mailer, and featured Greer's famous "Mozart's sister" speech, as well as her assertion that "male art is sapping our vitality and breaking our hearts". Where, Trilogy makes you wonder, as you see one simplistic magazine article after another talking about women "juggling" busy lives, did the passion of that debate go?

Part three, with its shocking images of genital mutilation and a woman being stoned to death, makes you wonder how far we've really come. Then, just when you're feeling down, it suggests cunning ways in which women can take control of their own destinies and forge a future. After the final singalong, Trilogy sends its audience out into the night feeling that something has begun, not ended – floating on the high notes of Jerusalem and our own euphoria.